Many prescribed drugs are designed to be taken at regular intervals during the day to achieve their proper effect. In fact, in certain diseases, such as heart disease and in the control of diabetes and blood pressure, missed dosages can prove quite serious. This is particularly common with the elderly and infirm since such patients have some difficulty recalling the time at which a previous dose of medicine was taken or even whether it was taken at all. Furthermore, such patients often must be reminded when the correct time comes to take the medication.